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Discussion Starter #1 (Edited)
Hey everyone,

I am aware that this is a common problem with the 1098 engine. My problem just started though at 22k miles where I would sit at stoplights or in traffic at idle and the bike would just shut off. I know that this engine is not very good at idle. I've been trying out a few things myself like changing out the fuel filter, changing the voltage regulator, sync the throttle bodies, balance the throttle bodies, change the spark plugs, change timing belts, and bypass the kick stand sensor. I'm pretty familiar with my bike, but I went the dealer to see if i'm missing anything and they couldn't tell me anything either, which is a joke. But today, I did take off the air intake box to look and see if there was any junk inside and I noticed some damaging on the front throttle body which can be seen in the photos below. The photos with the red circles are the front throttle body. The other photo is the rear throttle body. The rear throttle body is flush, but the front one seems like something got inside the air box and was making it scratch the rim. Could this be throwing my bike off at idle and causing it to shut off at stop lights?

Another assumption that I'm making is a vapor lock in the fuel lines. The fuel lines sit literally right on top of the rear engine head. I was thinking when the bike is idling at stand still, maybe it gets too hot and starts creating vapor bubbles within the fuel line, which could cause it to shut off and could also explain why it struggles to turn back on after it shuts off. Not sure if this is the problem though. I was going to put some high temperature tape around the fuel lines and test that out to see if it works once I get the throttle bodies back on.

If anyone could give me any feedback on this, I would deeply appreciate it.
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You didn't mention a TPS reset or cable adjustment. Idle is not a a problem on the SF, off idle fueling is.
 

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is the idle speed correct? it's run by the ecu via the idle valve. it should be annoyingly high, like 1500.

if the idle control system is ok, they stall because they don't have enough cylinder pressure to overcome the drag.

the drag comes from the main bearings being over preloaded at the factory. yours was ok before, so that's not "the" issue, but is probably partly provoking it now. or maybe something else inside it that would be considered "something wrong with it" as opposed to a tuning issue as such.

rich at luigi moto had a chronic stalling 749s years ago that didn't respond to the usual and eventually they pulled and split it and found the crank was very tight. reshimmed it, never an issue again. drastic, but ultimate solution.

cylinder pressure issue can be loose closing clearances or cam timing with too much overlap (reduced lobe separation). i do the cam timing on a lot of 1098/11989, and i find a 5 degree reduction in separation on an 1198 (moving one cam 5 degrees or both 2.5 degrees) is enough to make a bike that stalled very occasionally do it much more regularly. probably again bikes with a combination of small issues. in that case, the band aid fix is more ignition advance at idle in the ecu file. another 5 - 8 or so degrees fixes them.
 

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Discussion Starter #4 (Edited)
is the idle speed correct? it's run by the ecu via the idle valve. it should be annoyingly high, like 1500.

if the idle control system is ok, they stall because they don't have enough cylinder pressure to overcome the drag.

the drag comes from the main bearings being over preloaded at the factory. yours was ok before, so that's not "the" issue, but is probably partly provoking it now. or maybe something else inside it that would be considered "something wrong with it" as opposed to a tuning issue as such.

rich at luigi moto had a chronic stalling 749s years ago that didn't respond to the usual and eventually they pulled and split it and found the crank was very tight. reshimmed it, never an issue again. drastic, but ultimate solution.

cylinder pressure issue can be loose closing clearances or cam timing with too much overlap (reduced lobe separation). i do the cam timing on a lot of 1098/11989, and i find a 5 degree reduction in separation on an 1198 (moving one cam 5 degrees or both 2.5 degrees) is enough to make a bike that stalled very occasionally do it much more regularly. probably again bikes with a combination of small issues. in that case, the band aid fix is more ignition advance at idle in the ecu file. another 5 - 8 or so degrees fixes them.
I believe the idle is correct, its around 1250 rpm +/-50. Is the idle speed supposed to be the high on the 1098? I thought it was around 1300 rpm? If it is I can go ahead and set mine at that and see where that takes me. The idle control system seems to operate correctly, since the bike keeps a constant rpm the whole time it's idling, even when the engine is up to temperature.
 

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Discussion Starter #5
You didn't mention a TPS reset or cable adjustment. Idle is not a a problem on the SF, off idle fueling is.
I balanced the throttle bodies and also synced them as well. But this seemed to not be the problem. Could this TPS reset be done myself? I usually try to stay away from the dealers since they charge outrageous prices.
 

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I balanced the throttle bodies and also synced them as well. But this seemed to not be the problem. Could this TPS reset be done myself? I usually try to stay away from the dealers since they charge outrageous prices.
Sure with a few cables, an app or pc software (see tuneecu on Android, jpdiag or guzzydiag on pc).

Vapor lock is a gravity fed carb thing, never heard of this on pressurized fuel rail.
 

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Discussion Starter #7
Sure with a few cables, an app or pc software (see tuneecu on Android, jpdiag or guzzydiag on pc).

Vapor lock is a gravity fed carb thing, never heard of this on pressurized fuel rail.
Thank you! I'll try this out.
 

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Does it shut off suddenly or gradually slows and dies? I recently had latter start to happen on my 2010 SFS. Almost the same sensation that you ran out of gas but it ran great while on the go. It would start fine on occasion but became bad enough that I couldn't get to the end of my driveway without it dying when I came to a stop.

I did many of the things you did, but the only thing that has made a difference so far was to degree the cams. Both the intake and exhaust on the horizontal cylinder were 5-10 degrees out of spec.

I only got to ride it today but it did my morning commute with no issues. I did the work this past Sunday and it took the afternoon to complete. It is not technically difficult but you do need some special tools, a dial indicator and stand, to do.
 

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Discussion Starter #9
Does it shut off suddenly or gradually slows and dies? I recently had latter start to happen on my 2010 SFS. Almost the same sensation that you ran out of gas but it ran great while on the go. It would start fine on occasion but became bad enough that I couldn't get to the end of my driveway without it dying when I came to a stop.

I did many of the things you did, but the only thing that has made a difference so far was to degree the cams. Both the intake and exhaust on the horizontal cylinder were 5-10 degrees out of spec.

I only got to ride it today but it did my morning commute with no issues. I did the work this past Sunday and it took the afternoon to complete. It is not technically difficult but you do need some special tools, a dial indicator and stand, to do.
Once the bike is to temperature, it will shut off suddenly in neutral at idle (sometimes), it has never done it while in gear. It doesn't sound pleasant either. It makes like a clunk sound when it dies (this clunk sound it makes only happens once when it does dies). And when I try to start it up again, it struggles to turn back on, where the voltage will drop down to like 9 volts which is draining way too much voltage. And while I try to start it up it will make that clunk sound 1 more time.
 

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Discussion Starter #11
sounds like it's got starter clutch and maybe charging issues too.
I was noticing that too. I don't think there's any charging issues since I've tested the voltage with a multimeter after it shuts off and it read 13.54 volts. It's most likely a bad starter since it drags that many volts to turn back on, so I'll probably get the starter rebuilt or buy purchase a new one.
 
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